How to Use TLP3555A Photorelay: Examples, Pinouts, and Specs

The TLP3555A is an optically isolated photorelay manufactured by Toshiba. It is designed to control high voltage and high current loads using low voltage input signals. This solid-state relay utilizes an LED and a photodetector to achieve electrical isolation between the input and output, ensuring safe and reliable operation in various applications.

The TLP3555A is widely used in:

• Industrial automation: For controlling motors, solenoids, and other high-power devices.
• Telecommunications: For signal routing and switching.
• Power management: In systems requiring high-speed switching and isolation.

Its compact design, high-speed switching capability, and robust isolation make it an ideal choice for applications requiring reliable and efficient load control.

The TLP3555A is housed in an 8-pin DIP package. The pinout is as follows:

1. Input Side (Control Signal):

   • Connect the Anode (Pin 1) to the positive side of the control signal (e.g., a microcontroller GPIO pin).
   • Connect the Cathode (Pin 2) to ground through a current-limiting resistor. The resistor value can be calculated using Ohm's law: [ R = \frac{V_{control} - V_f}{I_f} ] Where (V_{control}) is the control signal voltage, (V_f) is the forward voltage of the LED (1.2 V typical), and (I_f) is the desired forward current (e.g., 10 mA).

2. Output Side (Load Control):

   • Connect Drain (D1, Pin 5) and Drain (D2, Pin 7) to the load or power source.
   • Connect Source (S, Pin 6) to the other side of the load or ground, depending on the circuit configuration.

3. Power Considerations:

   • Ensure the load voltage and current do not exceed the maximum ratings (600 V, 4 A).
   • Use proper heat dissipation techniques if operating near the maximum current rating.

4. Isolation:

   • The TLP3555A provides 5000 Vrms isolation between the input and output, making it suitable for high-voltage applications.

The TLP3555A can be controlled using an Arduino UNO. Below is an example circuit and code to toggle a load using the photorelay.

• Connect Arduino digital pin 9 to the Anode (Pin 1) of the TLP3555A through a 330 Ω resistor.
• Connect the Cathode (Pin 2) to Arduino GND.
• Connect the load (e.g., a 12 V motor) between the Drain (D1, Pin 5) and a 12 V power source.
• Connect the Source (S, Pin 6) to the ground of the 12 V power source.

// TLP3555A Photorelay Control Example
// This code toggles the photorelay on and off every second.

const int relayPin = 9; // Pin connected to the TLP3555A Anode

void setup() {
  pinMode(relayPin, OUTPUT); // Set relayPin as an output
}

void loop() {
  digitalWrite(relayPin, HIGH); // Turn on the photorelay
  delay(1000);                 // Wait for 1 second
  digitalWrite(relayPin, LOW);  // Turn off the photorelay
  delay(1000);                 // Wait for 1 second
}

• Use a current-limiting resistor on the input side to protect the LED.
• Avoid exceeding the maximum load voltage and current ratings.
• Ensure proper heat dissipation when operating at high currents.
• Verify the isolation voltage requirements in your application to ensure safe operation.

1. Can the TLP3555A be used with AC loads?

   • Yes, the TLP3555A can control AC loads, but ensure the load voltage and current are within the specified limits.

2. What is the maximum switching frequency?

   • The TLP3555A has a typical turn-on time of 3 ms and turn-off time of 1 ms, making it suitable for low to moderate switching frequencies.

3. Is additional isolation required for high-voltage applications?

   • The TLP3555A provides 5000 Vrms isolation, which is sufficient for most applications. However, additional isolation may be required for extremely high-voltage systems.

4. Can I use the TLP3555A with a 3.3 V control signal?

   • Yes, as long as the forward current of the LED is sufficient (e.g., 3 mA typical). Adjust the current-limiting resistor accordingly.

This concludes the documentation for the TLP3555A Photorelay. For further details, refer to the official Toshiba datasheet.